Furnace door operating mechanism



Feb. 12, 1946. w. B. LEVY FURNACE DOOR OPERATING MECHANISM Filed Nov. 18, 1942 2 Sheets-Sheet 1 w. B. LEVY Feb. 12, 1946.

. Filed Nov. 18, 1942 FURNACE DOOR-OPERATING MECHANISM 2 Sheets-Sheet 2 lw :5 5 230 2 i 2' Patented Feb. 12, 1946 UNITED STATES PATENT OFFICE FURNACE DOOR OPERATING MECHANISM William B. Levy, Wilmington, Del. Application November 18, 1942, Serial No. 466,048

7 Claims.

for balancing and operating the door of the furnace which, in the kind of furnace previously referred to, is of the vertically slidable type.

Heretofore, considerable diificulty has been ex perienced during the operation of the aforesaid type of furnace doors as a result of the doorjam- 'ming or binding in the guideways in which the door is slidably mounted.

Another difficulty encountered in the operation of 'the aforesaid type of furnacerdoors resides in the door having a tendency to creep open, in

some instances, and in other instances, to lose balance with its counter-weight, thereby requiring excessive manual labor to raise the door.

One object of the invention is to provide means whereby the balance between the door and its counter-weight may be readily adjusted, as the weight of the door changes under the circumstances hereinafter noted.

Another object of the invention is to provide means whereby the attachment point of the counter-Weight chain, or equivalent flexible elemeninmay be kept in line with the center of gravity of the door, to prevent jamming or binding of the door in its guides-ways.

In the accompanying drawings:

Fig. 1 is a face view of a furnace equipped with operating mechanism constructed and adapted to function according to the principles of the present invention;

Fig. 2 is an enlarged fragmentary longitudinal sectional view of the furnace, and its door, as taken on the line 22, Fig. 1;

Fig. 3 is a detached perspective view of the counterbalancing mechanism of the door;

Fig. 4 is a detached perspective view of the door; and

Fig. 5 is a detached perspective view of the door hanger.

As shown in Fig. 1, the furnace l is supported by a rigid framework 2, which includes vertical uprights 3, 3, and a horizontal cross member 4 at the top of the uprights 3, 3. Adjacent the bottom of the framework 2, the uprights 3', 3, are rigidly connected by a shelf 5, in the present instance.

The front face of the furnace I is provided with terior of the furnace. The entrance 6 is adapted to be closed by a vertically slidable door Ill, having vertical side flanges II, II which are respectively located in channel guides I2, l2 disposed at opposite sides respectively of the entrance 6. Below the bottom of the entrance 6 is a sill l3 on which the door I0 normall rests when in its lower entrance-closing position,

The weight of the door I 0 is adapted to be counterbalanced by a weight I 4 which is verti cally slidably mounted in a guide tube I5, The tube I5 is secured to one of the legs or uprights 3, in anysuitable manner, as by brackets l6, IS.

'The counter-weight I 4 is connected to the door H) by a chain, or other flexible connecter l'l,v

passing over a differential rocking lever I8, which latter is pivotally connected to the frame 2, at 19.

The lower end of the counter-weight i4 is provided with a foot treadle 20, which includesan arm 2|, secured to the lower end of the counterweight [4 and slidable in a vertical slot 22 formed in the lower end of the guide tube [5. If desired, the lower end of the slot 22 may be-laterally enlarged to provide a shoulder 23 under which the 7 upper edge of the arm 2| may be hooked by rotation of the arm2| slightl about the axis of the weight M. To assist the operator in raising the door In by placing his left foot, for example, on the treadle 20, the connecting chain I! is provided with a knurled hand grip 25.

The door I 0 includes a hollow integral main body structure which is preferably composed of cast iron or steel, and consists of a substantially flat rectangular front plate 26, a bottom marginal flange 21, a top marginal flange 28, and a pair of side marginal flanges 29, 29 disposed at acute angles to the front plate 26, and which converge toward the rear face 30 of the door It! Where the guide flanges II, II are located and extend laterally in opposite directions from the rear edges of the side flanges 29, 29, respectively.

The rear face 30 of the door casting is open and defined by the rear edges of the flanges 21, 28 and 29. The hollow interior of the door casting is provided with a body of heat-resisting material 3| preferably a suitable fire brick or its equivalent.

In assembling, the heat-resisting material 3! is initially in a plastic or semi-plastic state, and is moulded directly in the hollow interior of the door casting, with the rear face of the heatresisting material 3| flush with the rear edges of the marginal flanges 21, 28 and 29, coincident an entrance opening 6, by which themetal to be with the rear face 311 of the door. After mouldception of a locking pin 31.

ing, the material 3| is dried within the hollow casting. When the furnace to which the door is attached is put into operation, the extremely high temperatures, at which the furnace operates, eifect a super-drying of the material 3|, which produces a loss in weight of the door ID, as a whole.

When the furnace is first assembled, prior to initial operation, the counter-weight I4 is adjusted to balance the .weightof the-door |'|l,-so

that the door may be readily raised by a relatively light foot pressure on the treadle 20, supplemented, when desired, by a pull on the chain I! by gripping the handle 25 thereon.

In order to make the counter-balancing adjustment, the counter-weight M is preferablyprovided with a, plurality of supplementary weights 32, 32 which, as shown in Fig. 3 particularly, are recessed inwardly from the peripheral edges thereof, as indicated at 33, to pass around the countre-weight chain 11, whereby the supplemental weights '32 will rest directly on the top surface 34 of the counterweight'l4.

In order to prevent accidentaldisplacement of the supplementalweights 32, each of the said weights is provided withvan opening 35 which is adapted to be placed in vertical alignment with acorresponding opening 36 formed'in the upper surface 34 of the counter-weight M, for the re- The pin-31 fitsmore or less loosely through the openings 35 and 35 and locks the supplementary-weights 32 in position on the main weight 14. The lockingpin 31 is provided with a suitableknob or'head 38 by which the pin may be raised to permit 'removal of any one or all of th supplementary weights .After thefurnace I has been operated initially for a substantial period of time, and the superdrying of the heat-resisting material 3| has taken place, and the balance between the door I and the counter-balancing weights Hand 32 has'been disturbed, such balance may be readily restored by removing the supplementary weights 32, one after another, from time to time, as the superdrying of the material 3| progresses, whereby the :balance between the door and its counterbalancing mechanism may be maintainedat all times.

The above noted arrangement is particularly advantageous where the furnace is being used for annealing or temperingetmof small objects, where it is-necessary for the operator to open and close the door ||l frequently inthe treatment of large numbers of pieces. Thus, fatigue of the operator, for which the lifting of the heavy door is responsible, is reduced to a minimum, whereby a "his energy may be directed to the proper handling of the work rather than being expended in the operation of the door.

The hand grip 25 functions also as a safety device, toprevent the operators hand from being caught between the chain and the short-radius segment of the locker l8, when closing the door.

Invariably, the'natural and inherent instinct of the operator, whenoperating the door, is to grip the chain H with the left hand whileop'erating the door, primarily through the foot treadle, by the left foot while using the right hand at the same time, to place the work'in the furnace and to remove the work from the furnace.

By placing the grip 25 at the proper place in the chain I] with'respect to the rocker -:|8,'-when the door H) is closed, danger of injuring the fingers of the operator is obviated as theoperator ,ment fitting 41, said fitting having a vertical lug 48 to which oppositely disposed links of the chain Hare connectedby-a pin 49.

showniin Fig. 5, the fitting 41, by reason of the elongation of the bolt openings 45, is adapted'to be adjusted toward the rear face 30 of the door ill or toward the front face 26 thereof, whereby the center line or axis of the chain :ll may be placed in vertical alignment, fore and aft of the door 1-3, .with the center of .gravity of the door. adapted'to be adjusted laterally, abreast of the door I10, .by sliding thebolts-43iin either direc- Also, the fitting 41 'is tion, crosswiseof-the door, within the lug 40 in which the undercut {S1013 4| is formed. In this aligned with the 'center ,of gravity ,of the door the axis of :the chain |1 maybe accurately l3, thus making it possible for the-guide flanges ll of the door lll'to ridexfreely ancl'trulyimthe channels 2 withoutbinding therein.

Theabove alignment also adds to the ease of operation of the door and-contributes to the conservation of the energy of the operator when the .door of the furnace is necessarily operated at frequent intervals.

As disclosed in the aforesaid co-pendingapplication, the door flanges Ill, ||-may, if desired, be provided with wedge shaped lugs 50 which,'as the door approaches its closed position, engage the inner ends of adjustableabutment screws 5| which move the door toward :the front of the furnace until the rear face '33 thereof engages the front face 52 of face tile'53 which frame'the opening 6 of the furnace, thereby effectivelyseal- 'ing the furnace entrance against loss of :heat

around the door whenclosed.

'Whenlarge pie'cesof work are being treated in the furnace, which require :the :use of both the operators handsand that both of his-feet-remain on the floor, for stability, or :when small pieces of a particular nature requiring quick operation of 'thedoor by one attendant,.while.anothermakes the work transfer into and "out of the furnace,.or in any other instance which may require the service of a special operator for the door while another handles the work, the handle 25 on the chain H is used, in many cases exclusively,'lto operate the door, by -the door-attendant standing to one side, out of the work-attendants 'way. This is'made possible by reason of the door'being kept substantially in balance, with just enough over-balance in favor of the door to keep'lt seated on the sill, against creeping.

I claim: 1. Operating mechanism for a vertically slidable furnace door, comprising a counter-weight for the door, a flexible element operatively connecting the door and the counter-weight, :means for attaching one end of said flexible element to the top of said door comprising a fitting secured to said one end of said flexible element andadapted to beadjustably mountedon the top of said door, said top an'dsaid fitting being respectively provided with intersecting bolt slots, and bolts mounted in said slots for securing said fitting to said top, said intersecting slots affording universal horizontal adjustability of said fitting relative to said top.

2. Operating mechanism for a vertically slidable furnace door, comprising a counter-weight for said door, a motion multiplying rocker lever comprisinga short arm and a long arm above said door and said counter-weight and in a common vertical plane therewith, flexible means connecting the long arm of said rocker with said door and the short arm thereof to said counter-weight, the weight of said door being variable under conditions of use of the furnace, manual operating means for the door connected to the short arm of said rocker lever, and means for varying the weight of said counter-weight in accordance with predetermined variations in the weight of the door.

3. Operating mechanism for a vertically slidable furnace door, comprising a counterweight for the door, a rocker above the door and counterweight and in a common vertical plane therewith,

flexible means connecting the rocker with the door and the counter-weight, a foot treadle connected to the lower end of counter-weight for operating the door, and arcomplementary hand grip on said flexible means intermediate said rocker and said counter-weight in predetermined relation to said foot treadle for simultaneous operation therewith for facilitating the operation of the door.

4. Operating mechanism for a vertically slidable furnace door, comprising a cylindrical counter-weight for the door, a tubular guide for the counter-weight, a rocker above the door and own-- ter-weight, flexible means connecting the rocker with the door and the counter-weight, a foot treadle connected to the lower end of counterweight for operating the door and having a portion projecting through a slot in said tubular guide, a shoulder formed in said slot for engagement with said treadle when rotated slightly about the axis of said counter-weight, and a complementary hand grip on said flexible means intermediate said rocker and said counter-weight in predetermined relation to said foot treadle for simultaneous operation therewith for facilitating the operation of the door.

5. Operating mechanism for a vertically slidable furnace door, comprising a flexible element for raising and lowering said door, an attachment fitting connecting said element to the top surface of the door, an elongated lug integral with said door and projecting above said top surface with an undercut slot extending longitudinally of said lug, said fitting having transverse slots adapted to lie in intersecting relation to said undercut slot, and bolts extending through said slots at said intersections for securing said fitting to said lug, said intersecting slots affording universal horizontal adjustability of said fitting relation to said door for aligning the point of attachment of said flexible element relative with the center of gravity of the door.

6. Operating mechanism for vertically slidable furnace doors, comprising a flexible element for raising and lowering said door, an undercut slot formed in the top of the door, an attachment fitting connected to said flexible element and superposed above said slot, a pair of elongated slots formed in said fitting at right angles to said undercut slot, and bolts passing through said elongated slots and said undercut slot to afford horizontal universal adjustment of said fitting relative to said door for aligning said flexible element with the center of gravity of said door.

7. Operating mechanism for vertically slidable furnace doors, comprising a counter-weight for said door, a motion multiplying rocker lever comprising a short arm and a long arm above the door and the counter-weight and in a common vertical plane therewith, a flexible element connecting the short arm of the rocker to the counter-weight and the long arm of the rocker to the door, the door being subject to manual actuation by operators of various weights and physical abilities and the weight of said door being subject to variation during operation of the furnace, manual operating means for the door connected to the short arm of said rocker lever, a seriesv of supplemental weights on top of and axially aligned with said counter-weight and recessed to fit around said flexible element to compensate for said variations in operation of said door, said counter and supplemental weights having alignable openings formed therein, and a locking pin fitting through aligned openings in said supplement weights and in said counter-weight to maintain substantial alignment therebetween.

WILLIAM B. LEVY. 

